The technical field of this invention is control of deployable occupant restraints in vehicles.
Deployable occupant restraints have been used to mitigate occupant injuries in vehicle crashes. These restraints are typically stowed in an inactive state to save space or to meet other normal vehicle operating needs and are activated into their occupant restraining configurations in response to detection of a vehicle crash by a sensor system. The restraints then serve to reduce the effects of a secondary impact between the occupant and the portion of the vehicle the occupant strikes. The sensor system must be able to predict the need for restraint deployment well in advance of the time the restraint must be in place to protect the occupant. Such predictions generally involve some method of assessing the probability of occupant injuries for a given crash. These assessments are generally made by conducting and analyzing a multitude of crash tests for a given vehicle design using highly instrumented dummies and determining a few key calibration factors that are hard coded into the restraint deployment control. Such calibration factors generally apply regardless of the characteristics of the vehicle occupant or occupants protected by the restraint(s) of a vehicle at any given time. As knowledge of the performance of the restraints has grown with industry experience, pressure has grown for more sophisticated controls which can distinguish various types of vehicle occupants and tailor the deployment of an occupant restraint to a particular type of occupant. Ideas and designs for such systems are showing up in publications; and requirements concerning such controls are appearing in scheduled governmental regulations. But the proposed designs are generally complicated; and compliance with the regulations is proving difficult due to the complexity of the situation.
This invention is a vehicle restraint control system that provides sophisticated, adaptable control of occupant restraints through the use of a system level architecture to predict the nature of a crash event at the earliest possible time and a crash severity model to tailor the restraint deployment in an adaptable way to characteristics of the protected vehicle occupant(s) and the nature of the crash event. The crash severity model derives the potential for occupant injury in a particular vehicle crash in real time as a function of a predicted occupant impact velocity with respect to the vehicle interior and preferably also with respect to occupant mass and vehicle interior stiffness. The model may adjust the predicted occupant impact velocity in response to derived impact angle.
In a preferred embodiment, the system determines a peak vehicle crush zone velocity, a vehicle occupant mass, an interior vehicle stiffness and a longitudinal velocity of the vehicle occupant compartment, derives crash severity datum from these determined parameters and determines whether to deploy an occupant restraint at least in response to the crash severity datum. In this embodiment, the peak vehicle crush zone velocity is used as a predictor of occupant impact velocity with the vehicle interior.
In another embodiment, the system additionally determines a lateral velocity of a vehicle occupant compartment, derives an impact angle factor from the lateral velocity of the vehicle occupant compartment and the longitudinal velocity of the vehicle occupant compartment and additionally derives the crash severity datum from the impact angle factor. In another embodiment, the system derives a predicted occupant displacement datum from a time integration of the longitudinal velocity of the vehicle occupant compartment and prevents deployment of the restraint when the occupant is too close to the vehicle interior for the restraint to offer significant help.